1. Field of the Invention
This invention relates to an anti-reflection film of multiple layers for application to glass.
2. Description of the Prior Art
Conventional anti-reflection films have consisted of multiple layers formed by vaporizing MgF.sub.2 as a low refractive index substance and a transition metal oxide as a high refractive index substance alternately on a glass substrate.
However, MgF.sub.2 which is a low refractive index substance is low in packing density and therefore, even in room-temperature atmosphere, the Na.sup.+ or the Pb.sup.++ ions in the glass is caused by diffusion to pass through the layers of MgF.sub.2 and enter the layers of transition metal oxide which is a high refractive index substance, and the interaction between these Na.sup.+ or Pb.sup.++ ions and the transition metal oxide produces a light scattering product, thus aggravating the spectral reflection factor characteristic. Such a disadvantage has been peculiar to the conventional anti-reflection films.
The conventional anti-reflection films have also suffered from a disadvantage that the water vapor in the air passes through the multiple layers to create stain (tarnish) or white stain on the surface of the glass to thereby vary the refractive index of the glass surface or form a light scattering product thereon.